Using SiO₂ Hard Mask for Fabrication of Micro Fresnel Focusing Lens for Ultrasonic Ejectors

Abstract:

The fabrication of Fresnel focusing lenses operating at frequencies of 100 and 200 MHz was investigated in order to enhance the focusing efficiency of ultrasonic energy. The effects of process parameters on the four-level Fresnel lens profiles were discussed to find a most feasible fabrication procedure through these experiments. The quality of Fresnel lenses was improved when two-and three-mask processes using SiO2 film as the hard mask were employed. Besides, a better side-wall profile of Fresnel lens was obtained by using the three-mask process as compared to the two-mask one.

• Periodical: Key Engineering Materials (Volume 863)
• Pages: 73-78
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.863.73
• Online since: September 2020
• Authors: Tuan Anh Bui*, Min Chun Pan, Tzon Han Wu, Thanh Long Le
• Keywords: Fresnel Focusing Lens, Micro Fabrication, SiO₂ Hard Mask, Ultrasonic Ejectors

References

[1] B.H. S. A. Elrod, B. T. Khuri-Yakub, E. G. Rawson, E. Richley, C. F. Quate, N. N. Mansour, and T. S. Lundgren, Nozzleless Droplet Formation with Focused Acoustic Beams, J. Appl. Phys., 65 (1989) 3441-3447.

DOI: 10.1063/1.342663

[2] U. Demirci, Acoustic picoliter droplets for emerging applications in semiconductor industry and biotechnology, J. Microelectromech. Syst., 15 (2006) 957-966.

DOI: 10.1109/jmems.2006.878879

[3] H. Yu, Q. Zou, J.W. Kwon, E.S. Kim, Liquid Needle, J. Microelectromech. Syst., 16 (2007) 445-453.

[4] J.M. Meacham, M.J. Varady, F.L. Degertekin, A.G. Fedorov, Droplet formation and ejection from a micromachined ultrasonic droplet generator: Visualization and scaling, Physics of Fluids, 17 (2005) 100605.

DOI: 10.1063/1.1921249

[5] S.C. Tsai, C.H. Cheng, W. Ning, Y.L. Song, C.T. Lee, C.S. Tsai, Silicon-based megahertz ultrasonic nozzles for production of monodisperse micrometer-sized droplets, IEEE Trans. Ultrason., Ferroelectr. Freq. Control, 56 (2009) 1968-1979.

DOI: 10.1109/tuffc.2009.1273

[6] H. Fukumoto, J. Aizawa, H. Nakagawa, H. Narumiya, Printing with Ink Mist Ejected by Ultrasonic Waves, J. Imaging Sci. Technol., 44 (2000) 398-405.

[7] S. Kameyama, H. Fukumoto, T. Kimura, S. Wadaka, Ink Mist Jet Generation Using Low Frequency Focused Ultrasonic Waves and Nozzle, 1999 IEEE Ultrasonics Symposium, (1999) 695-698.

DOI: 10.1109/ultsym.1999.849493

[8] H. Fukumoto, J. Aizawa, H. Matsuo, H. Narumiya, K. Nakagawa, Liquid Ejector Which Uses a High-Order Ultrasonic Waves to Eject Ink Droplets and Printing Apparatus Using Same, in: U. patent (Ed.), (2000).

[9] J. Aizawa, H. Fukumoto, M. Takeda, Liquid Ejector, in: U. patent (Ed.), (2003).

[10] B. Hadimioglu, S.A. Elrod, D.L. Steinmetz, M. Lim, J.C. Zesch, B.T. Khuri-Yakub, E.G. Rawson, C.F. Quate, Acoustic Ink Printing, 1992 Ultrasonics Symposium, (1992) 929-935.

DOI: 10.1109/ultsym.1992.275823

[11] B. Hadimioglu, E.G. Rawson, R. Lujan, M. Lim, J.C. Zesch, B.T. Khuri-Yakub, C.F. Quate, High-Efficiency Fresnel Acoustic Lenses, 1993 Ultraoniscs Symposium, (1993) 579-582.

DOI: 10.1109/ultsym.1993.339544

[12] B. Hadimioglu, S. Elrod, R. Sprague, Acoustic Ink Printing: an Application of Ultrasonics for Photographic Quality Printing at High Speed, 2001 IEEE Ultrasonics Symposium, (2001) 627-635.

DOI: 10.1109/ultsym.2001.991808

[13] C.F. Quate, E.G. Rawson, B. Hadimioglu, Muti-Discrete-Phase Fresnel Acoustic Lenses and Their Application to Acoustic Ink Printing, in: U. patent (Ed.), (1991).

DOI: 10.1121/1.408439

[14] D. Huang, E.S. Kim, Micromachined Acoustic-Wave Liquid Ejector, J. Microelectromech. Syst., 10 (2001) 442-449.

DOI: 10.1109/84.946804

[15] M.-C. Pan, T.-A. Bui, Y.-C. Nien, W.-C. Shih, Design and Fabrication of Fresnel Lens and ZnO Thin-Film Transducer, Jpn. J. Appl. Phys., 50 (2011) 07HD02.

DOI: 10.7567/jjap.50.07hd02

[16] H. Xiao, Introduction to Semiconductor Manufacturing Technology, Prentice Hall, New Jersey, (2001).